The nontuberculous mycobacteria (NTM), especially the Mycobacterium avium complex (MAC), are among the most common opportunistic pathogens of AIDS patients. While a suite of effective diagnostic and therapeutic methods exist for Mycobacterium tuberculosis, far fewer such tools are available for combating disseminated NTM infections. In particular, prognostic antibiotic susceptibility testing of NTM is not routinely carried out, despite a high prevalence of resistant strains. This is partly because existing in vitro susceptibility tests developed for M. tuberculosis generally do not work well on NTM, and can require several weeks to yield results. The investigators have developed a new antibiotic susceptibility test which can potentially identify drug-resistant Mycobacterium tuberculosis strains within 1-4 days of sample acquisition. The method used by the investigators measures species-specific rRNA precursors (pre-rRNA) as molecular indicators of mycobacterial growth activity in the presence of antibiotics, and it is potentially more useful for NTM than existing methods. In the pilot research, the investigators propose to develop prototype pre-rRNA-based antibiotic susceptibility tests for the MAC, and conduct a nonclinical evaluation of their potential sensitivity and specificity. If sufficiently rapid and accurate, the availability of prognostic antibiotic susceptibility tests for the MAC could improve treatment outcomes, slow the selection of new resistant strains, and reduce exposure of patients to the unnecessary costs and adverse effects of futile treatments.